<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
   <style>
       div {
           float: left;
           width: 200px;
           height: 100px;
           background-color: pink;
           border: 1px solid black;
       }
   </style>
</head>
<body>
   <div>1</div>
   <div>2</div>
   <div>3</div>
   <script>
       var divs = document.querySelectorAll('div');
       divs[0].onclick = function() {
           alert('nihao');
           //传统方法删除事件
           divs[0].onclick = 'null';
       }

       divs[1].addEventListener('click',fn)
       function fn () {
           alert('buhao');
           //事件监听方法删除事件，
            divs[1].removeEventListener('click',fn);
       }
   </script>
</body>
</html>